Heat generating catalyst for hydrocarbons cracking

ABSTRACT

A method of making a heat generating catalyst for hydrocarbon cracking. The method includes providing at least one mordenite framework-inverted (MFI) zeolite having a Si/Al molar ratio of 15 or greater and providing at least one metal oxide precursor. Further, the at least one metal oxide precursor is dispersed within a microstructure of the MFI zeolite catalyst. The method additionally includes calcining the heat generating material with the at least one metal oxide precursor dispersed within the microstructure of the MFI zeolite catalyst to form at least one metal oxide in situ. The heat generating catalyst includes at least one MFI zeolite and at least one metal oxide in a ratio between 50:50 and 95:5. Additionally, an associated method of using the heat generating catalyst in a hydrocarbon cracking process is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 62/335,213 filed May 12, 2016, incorporated herein by reference.

BACKGROUND Field

Embodiments of the present disclosure generally relate to a heatgenerating catalyst for hydrocarbon cracking, and specifically relate toa method of making a heat generating catalyst and a method of using theheat generating catalyst in a hydrocarbon cracking process.

Technical Background

Current commercial technologies for production of light olefins, such asethylene and propylene, include thermal cracking or steam cracking aswell as catalytic cracking. Steam cracking is a non-catalytic processthat operates at elevated reaction temperatures of approximately 850° C.and requires steam dilution to control selectivity and maintainacceptable loop life. It is by far the most energy consuming process inthe chemical industry. It was found that the pyrolysis section of anaphtha steam cracker alone consumes approximately 65% of the totalprocess energy and accounts for approximately 75% of the total energyloss. Moreover, the process is extremely sensitive to feed variationsand raises several environmental concerns. It is not suitable formeeting the anticipated growing demand of propylene as it producesethylene as the primary product and it allows very little control overpropylene to ethylene (P/E) ratio. Conversely, catalytic cracking,particularly, fluidized catalytic cracking (FCC) with solid acidcatalysts produces products with relatively higher P/E ratios andoperates at lower temperatures of 500-650° C. In the FCC process, thecatalyst is suspended in a rising flow of feed hydrocarbons in afluidized bed. Pre-heated hydrocarbon feed is sprayed into the base ofthe frustum/riser via feed nozzles where it contacts hot fluidizedcatalysts at 500-650° C. The hot catalysts vaporize the feed andcatalyze the cracking reactions to break down the high molecular weightmolecules into lighter components including liquid petroleum gas (LPG),gasoline, and diesel. The “spent” catalyst then flows into afluidized-bed regenerator where air or in some cases air plus oxygen isused to burn off the coke to restore catalyst activity and also providethe necessary heat for the next reaction cycle. The “regenerated”catalyst then flows to the base of the riser, repeating the cycle.

The hydrocarbon cracking industry has invested significant efforts tomaximize the energy efficiency of endothermic hydrocarbon conversionprocesses, especially cracking, without compromising yields andconversion. For example, FCC is ideally thermo-neutral where cokecombustion in the regenerator fuels the endothermic cracking reaction.In reality, however, this heat generated from coke combustions is ofteninsufficient, especially for lighter feeds with high hydrogen/carbon(H/C) ratios. Several techniques have previously been employed toovercome energy deficiencies such as injecting excess air to promotecomplete combustion. However, injecting excess air significantlyincreases side reactions as well as operating and capital costs.Alternatively, injection of a calculated amount of an aromatic heavyfuel, known as torch oil, to the regenerator section has been attemptedto provide additional thermal energy. This method, while effective,usually results in the formation of non-oxidized cracked products. Thenon-oxidized crack products may cause formation of hot spots in thecatalyst bed, which, in the presence of steam, could cause deactivationand local permanent damages to the catalyst bed.

SUMMARY

In view of the provided background, an ongoing need exists for thedevelopment of efficient and economical routes to crack crude oil toyield high demand petrochemical building blocks including ethylene,propylene, butenes, benzene, toluene and xylene as well as otherhydrocarbons such as gasoline, atmospheric gas oil (ago), and vacuum gasoil (vgo).

Embodiments of the present disclosure are directed to methods of makingand using a heat generating catalyst in a hydrocarbon cracking processto fuel the energy requirements of endothermic hydrocarbon cracking. Themethods of the present disclosure have industrial applicability,specifically in the oil and gas industries due to the high energy coststraditionally required for hydrocarbon cracking. Without being limitedto theory, the heat generating catalysts of the present disclosure areadded to help the hydrocarbon cracking process become energy neutral orapproach energy neutrality, thereby reducing the overall energy costsassociated with hydrocarbon cracking.

According to one embodiment, a method of making a heat generatingcatalyst for hydrocarbon cracking is provided. The method includesproviding at least one mordenite framework-inverted (MFI) zeolitecatalyst having a Si/Al molar ratio of 15 or greater and providing atleast one metal oxide precursor. Further, the method includes dispersingthe at least one metal oxide precursor within a microstructure of theMFI zeolite catalyst. Subsequently, the method includes calcining themetal oxide precursor impregnated MFI zeolite catalyst to form a heatgenerating catalyst. The ratio of MFI zeolite catalyst to metal oxide isin the range of 50:50 to 95:5 on a weight basis. The catalyst could befurther modified with binders, clays, dispersants and other additives.

According to another embodiment, a method of using a heat generatingcatalyst in a hydrocarbon cracking process is provided. The methodincludes providing a catalyst bed reactor which includes a catalyst bedof the heat generating catalyst disposed in the catalyst bed reactor.The heat generating material is formed from at least one mordeniteframework-inverted (MFI) zeolite catalyst having a Si/Al molar ratio of15 or greater and at least one metal oxide dispersed within amicrostructure of the MFI zeolite catalyst. The method further includesintroducing a hydrocarbon feed to the catalyst bed reactor and crackingthe hydrocarbon feed to produce a cracking product. According to atleast one embodiment, the cracking product includes light C₁-C₄hydrocarbons.

Additional features and advantages of the described embodiments will beset forth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the described embodiments, including thedetailed description which follows, the claims, as well as the appendeddrawings.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the claimed subject matter. The accompanyingdrawings are included to provide a further understanding of the variousembodiments, and are incorporated into and constitute a part of thisspecification. The drawings illustrate the various describedembodiments, and together with the description serve to explain theprinciples and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a lab-scale reactor system foroperation in accordance with one or more embodiments of the presentdisclosure.

FIG. 2 is a back-scattered electron scanning electron microscopy imageof CuO/H-ZSM-5 catalyst in accordance with one or more embodiments ofthe present disclosure.

FIG. 3 is temperature programmed reduction test for 20% CuO supported onAlumina.

FIG. 4 is a catalyst bed temperature profile for CuO/H-ZSM-5 andunmodified H-ZSM-5 at a weight hourly space velocity of 3.5 hr⁻¹ andinitial temperature of 550° C.

FIG. 5 is a catalyst bed temperature profile for CuO/H-ZSM-5 andunmodified H-ZSM-5 at a weight hourly space velocity of 8.4 hr⁻¹ andinitial temperature of 550° C.

FIG. 6 is a catalyst bed temperature profile for CuO/H-ZSM-5 at a weighthourly space velocity of 8.4 hr⁻¹ and initial temperature of 550° C. andCuO/H-ZSM-5 at a weight hourly space velocity of 8.4 hr⁻¹ and initialtemperature of 588° C.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments for methods ofmaking a heat generating catalyst for hydrocarbon cracking and theimproved cracking of a hydrocarbon feed using the heat generatingcatalysts of the present disclosure. As stated previously, hydrocarboncracking is an endothermic process. By combining a cracking catalystwith a heat generating metal oxide, the traditionally endothermichydrocarbon cracking process can become thermally neutral or approachthermal neutrality. Specifically, the metal oxides dispersed throughoutthe cracking catalyst generate exothermic heat through a reductionreaction in a reactor when included in the hydrocarbon crackingprocesses of the present disclosure. This exothermic heat may provideadditional heat needed for the endothermic hydrocarbon cracking process.Additionally, an oxidation reaction in a regenerator when the reducedcatalyst is exposed to oxidizing conditions generates additional heat.The heat generated in the regenerator from the oxidation reactionincreases the temperature of the heat generating catalyst which in turnincreases conversion of the hydrocarbon feed when the heat generatingcatalyst is recycled back into the reactor.

A method of making a heat generating catalyst for hydrocarbon crackingis provided. A cracking catalyst and at least one metal oxide precursorare combined together. Specifically, the at least one metal oxideprecursor is dispersed within a microstructure of the cracking catalyst.With the at least one metal oxide precursor dispersed within themicrostructure of the cracking catalyst, the heat generating catalyst iscalcined to convert the at least one metal oxide precursor into at leastone metal oxide.

In at least one embodiment, The ratio of MFI zeolite catalyst to metaloxide in the heat generating catalyst is between 50:50 and 95:5 on aweight basis. There is a trade-off between catalyst and metal oxidepercentages. Specifically, increases in the weight percentage of metaloxide provide additional heat generating metal oxide during thereduction reaction allowing for hotter or longer sustained heatgeneration. However, an increase in metal oxide percentage may result inreduced catalyst activity of the MFI zeolite catalyst. In variousfurther embodiments, the ratio of MFI zeolite catalyst to metal oxide inthe heat generating catalyst is between 70:30 and 85:15 on a weightbasis, between 70:30 and 80:20 on a weight basis, and between 75:25 and85:15 on a weight basis. In at least one embodiment, the ratio of MFIzeolite catalyst to metal oxide in the heat generating catalyst isbetween 79:21 and 81:19 on a weight basis. Without wishing to be boundby theory, it is believed that the metal oxide may modify the acid siteson the MFI zeolite in a way that may affect the cracking activity inaddition to generating heat. The modification of the acid sites mayultimately increase or decrease the catalyst activity of the MFI zeolitecatalyst and adjust the selectivity of resultant species on the productstream. The modification of acid sites is dependent upon the metaloxide, the MFI zeolite, and the quantities of each utilized in the heatgenerating catalyst.

Various components are contemplated for the cracking catalyst. In one ormore embodiments, the cracking catalyst may include an aluminosilicatezeolite, a silicate (for example, silicalite), or a titanosilicate. Infurther embodiments, the solid acid cracking catalyst is analuminosilicate zeolite having a Mordenite Framework Inverted (MFI)structure. For example and not by way of limitation, the MFI zeolitecatalyst may be a ZSM-5 catalyst. In a further embodiment, the ZSM-5catalyst may be an H-ZSM-5 catalyst where at least a portion of theZSM-5 catalyst ion exchange sites are occupied by H+ ions. Moreover, theMFI zeolite catalyst, for example, the H-ZSM-5 catalyst, may have aSi/Al molar ratio of at least 15. In further embodiments, MFI zeolitecatalyst may have a Si/Al molar ratio of at least 20, or at least 35, orat least 45. Additionally, the MFI zeolite catalyst may have an averageparticle size may vary depending on the application for use. Forexample, the MFI zeolite catalyst may have an average particle size of50 to 120 micrometers (μm) when used in a fluid catalyzed application or1/16″ to ¼″ when used in a fixed bed application.

Moreover, the metal oxide precursor is dispersed within themicrostructure of the cracking catalyst and calcined in-situ to convertthe metal oxide precursor to a metal oxide. Dispersion of the at leastone metal oxide precursor within the microstructure of the crackingcatalyst provides the metal oxide in close proximity to the endothermiccracking sites of the cracking catalyst, thereby making the heatgenerating aspect of the heat generating catalyst more effective.Dispersion of the at least one metal oxide precursor within themicrostructure of the cracking catalyst is contrasted with mere physicalmixing of a cracking catalyst and a metal oxide. Physical mixing onlyprovides the metal oxide to the endothermic cracking sites of thecracking catalyst near the surface of the particles of the crackingcatalyst and not near the additional endothermic cracking sites withinthe microstructure of the cracking catalyst. Dispersion of the metaloxide precursors throughout the microstructure of the cracking catalysthelps avoid temperature gradients in the catalyst bed and hot spotswithin the catalyst bed which may result from merely physically mixing acracking catalyst and metal oxides. It will be appreciated that the heatgenerating catalyst may be provided to a hydrocarbon cracking systemwith the metal oxide precursor in a reduced form which is subsequentlyoxidized to a metal oxide by a first passage though a regenerator duringoperation of the hydrocarbon cracking system.

In various embodiments, the at least one metal oxide precursor isdispersed within the microstructure of the cracking catalyst via atleast one of wet impregnation, dry impregnation, incipient wetnessimpregnation, precipitation, ion exchange, electrolysis deposition,deposition-precipitation, chemical vapor deposition, and flame spraypyrolysis. Each method allows the metal oxide precursor to be dispersedthroughout the microstructure of the cracking catalyst which is notpossible with mere physical mixing. In various embodiments the metaloxide is dispersed throughout the microstructure of the crackingcatalyst. In one or more embodiments, the dispersing of the metal oxideprecursor within the microstructure of the cracking catalyst comprisesthe step of dissolving the metal oxide precursor in an organic solvent,for example methanol, ethanol, acetone or water, and adding drop-wise tothe cracking catalyst while stirring the resulting heat generatingcatalyst. In further embodiments, the method additionally includesdrying the cracking catalyst with the metal oxide precursor dispersedwithin the microstructure of the cracking catalyst. The drying procedurecomprises drying at 90° C. to 120° C. for at least 1 hours. Furtherembodiments, include drying at 90° C. to 120° C. for at least 3 hours,drying at 95° C. to 115° C. for at least 3 hours, and drying at 98° C.to 112° C. for at least 3 hours.

As previously indicated, the cracking catalyst with the metal oxideprecursor dispersed within the microstructure of the cracking catalystis calcined to generate metal oxides in-situ. In one or moreembodiments, the calcining of the heat generating catalyst comprisingthe cracking catalyst with the metal oxide precursor dispersedthroughout the microstructure of the cracking catalyst is achieved inair at 400° C. to 800° C. The calcining procedure is extended forsufficient time to convert the metal oxide precursor to a metal oxidein-situ, typically for 3 hours or more. Further embodiments, includecalcining at 700° C. to 800° C. for at least 3 hours, calcining at 550°C. to 650° C. for at least 4 hours, and drying at 600° C. to 700° C. forat least 3 hours.

The conversion of the metal oxide precursor to a metal oxide providessites dispersed throughout the microstructure of the cracking catalystfor heat generation as a result of a reduction reaction of the metaloxide. In at least one particular embodiment, the generated metal oxideis a copper oxide. In various embodiments, the metal oxide is at leastone of an oxide of iron, copper, zinc, chromium, molybdenum, vanadium,cerium, manganese, bismuth, silver, cobalt, vanadium, zirconium,tungsten, magnesium, and their combinations.

In at least one embodiment, the metal oxide precursor is a hydrate of ametal salt of nitric acid. Non-limiting examples include, copper nitratetrihydrate (Cu(NO₃)₂.3H₂O), cobalt(II) nitrate hexahydrate(Co(NO₃)₂.6H₂O), and chromium (III) nitrate nonahydrate (Cr(NO₃)₃.9H₂O).

The at least one metal oxide dispersed within the microstructure of thecracking catalyst is chemically bonded to the microstructure.Impregnation or other dispersion techniques pushes the metal oxideprecursor inside the microstructure of the cracking catalyst, converselymerely physical mixing keeps the cracking catalyst and metals oxideparticles completely separate. Further, impregnation may bind the oxidemetals chemically to the functional groups in the catalyst surface andinside pores. Dispersion within the microstructure of the crackingcatalyst also places metal oxides close to the active sites in thecatalyst, conversely physical mixing keeps the metal oxides and theactive sites in the catalyst separated.

In one or more embodiments, the heat generating catalyst furthercomprises a promoter. Non-limiting examples of promoters include analkali metal, an alkaline earth metal, a rare earth metal, a transitionmetal, phosphorous, and their combinations.

The created heat generating catalyst for hydrocarbon cracking may beutilized in a hydrocarbon cracking system in a hydrocarbon oxidativecracking process. The hydrocarbon cracking system of FIG. 1 is alaboratory set-up provided for the present discussion which follows;however, it should be understood that the present systems and methodsencompass other configurations including large-scale and industrialprocess schemes.

Referring to the embodiment of FIG. 1, a laboratory scale hydrocarboncracking system 100 with at least one catalyst bed reactor 10 forcracking a hydrocarbon feed 4 is shown. Specifically, the hydrocarboncracking system 100 performs catalytic hydrocarbon cracking of ahydrocarbon feed 4 with the heat generating catalyst discussedpreviously forming a catalyst bed in the catalyst bed reactor.

The hydrocarbon feed 4 may refer to any hydrocarbon source derived frompetroleum, coal liquid, or biomaterials. Example hydrocarbon sourcesinclude whole range crude oil, distilled crude oil, residue oil, toppedcrude oil, liquefied petroleum gas (LPG), naphtha, gas oil, productstreams from oil refineries, product streams from steam crackingprocesses, liquefied coals, liquid products recovered from oil or tarsands, bitumen, oil shale, biomass hydrocarbons, and the like. Inspecific examples, which will be described in subsequent paragraphs, thehydrocarbon feed 4 may include n-hexane, naphtha, mixed butenes, andethylene. C4-C5, C9 and C9+ hydrocarbons may be included to re-crack andgenerate value added components when demand for such components iselevated. The n-hexane is just one example of a long chain hydrocarbon,which is presently defined as hydrocarbon carbon chains having at leastsix carbons.

Referring again to FIG. 1, the hydrocarbon cracking system 100 maycomprise a reactor system having at least one catalyst bed reactor 10,and optionally, additional reactors and units. For example, theseadditional optional units may include a preheater 12 connected to the atleast one catalyst bed reactor 10 and additional heaters or heatexchangers 18.

As shown, the catalyst bed reactor 10 may include a catalyst bed 14 ofthe heat generating catalyst disposed in the catalyst bed reactor 10. Asstated previously, the operation of the catalyst bed reactor 10 resultsin the cracking of the hydrocarbon feed 4 to produce a cracking product40, where the cracking product 40 comprises light C₁-C₄ hydrocarbons,such as ethylene and propylene, and heavy C₅+ hydrocarbons. The crackingproduct 40 may also comprise BTX aromatics (benzene, toluene, and xyleneisomers). The ratio of components in the cracking product 40 variesdepending on the feed type, reaction parameters, and catalystparameters. Utilizing the heat generating catalyst as the catalyst bed14 of the catalyst bed reactor 10 reduces or eliminates the additionalheat energy input requirements in the catalyst bed reactor 10.Specifically, the heat generating catalyst undergoes an exothermicreaction in the catalyst bed reactor 10 as the metal oxide is reducedwhich offsets the endothermic cracking process yielding a thermallyneutral overall hydrocarbon cracking operation. Additionally, in one ormore embodiments, the reduced metal oxide may be regenerated in anoxidizing atmosphere to generate additional heat release.

Additionally, hydrogen elimination by the metal oxides as a result oftheir reduction reactions limits hydrogen transfer reactions and as aresult promotes hydrocarbon cracking toward light olefins. The removalof the hydrogen from the product stream also eliminates the costly anddifficult process of separating the resulting light olefins fromhydrogen.

In one or more embodiments, the catalyst bed reactor 10 may be afixed-bed reactor, a fluidized bed reactor, a slurry reactor, or amoving bed reactor. In a specific embodiment, the catalyst bed reactor10 is a fixed-bed reactor. In some embodiments with a fixed bed reactor,the residence time of the combined hydrocarbon feed 4 and the heatgenerating catalyst stream 2 in the catalyst bed reactor 10 is in therange of 0.05 seconds to 1 hour. For example, the residence time mayapproach 1 hour for diesel hydrotreating a liquid feed and is generallyin the range of 0.1 to 5 seconds in an FCC application. As such, invarious embodiments, the residence time in the catalyst bed reactor 10is 0.1 seconds to 5 seconds or 5 minutes to 1 hour. The desiredresidence time in a fixed bed reactor of the combined hydrocarbon feed 4for optimal hydrocarbon cracking is dependent on operating temperatureand composition of both the heat generating catalyst and the hydrocarbonfeed 4. Additionally, in one or more embodiments, the bed voidage, whichrepresents the volume fraction occupied by voids, is between 0.2 and1.0. In further embodiments, the bed voidage is between 0.3 and 0.8.

Additionally, in one or more embodiments with a fixed bed reactor, thecatalyst bed 14 of the heat generating catalyst comprises a layer ofheat generating catalyst comprising the cracking catalyst with the metaloxide dispersed within the microstructure disposed before a layer ofunmodified cracking catalyst. In further embodiments, the catalyst bed14 of the heat generating catalyst comprises a layer of heat generatingcatalyst comprising the cracking catalyst with the metal oxide dispersedwithin the microstructure disposed after a layer of unmodified crackingcatalyst. In additional embodiments, the catalyst bed 14 of the heatgenerating catalyst may comprise a layer of the heat generating catalystcomprising the cracking catalyst with the metal oxide dispersed withinthe microstructure disposed between a least two layers of unmodifiedcracking catalyst.

Additionally, in one or more embodiments with a fluidized bed reactor,the catalyst bed 14 comprises a mixture of heat generating catalyst andthe cracking catalyst without metal oxide dispersed within itsmicrostructure.

Moreover, the catalyst bed 14 may be preheated. In one or moreembodiments the catalyst bed 14 is heated using steam or hot gases intubes passing through the catalyst bed reactor 10. In furtherembodiments the catalyst bed 14 is preheated in a gas flow containingheated nitrogen 6 and oxygen at sufficient flow rate to heat thecatalyst bed 14. The preheated gas flow or steam is heated from 450° C.to 650° C., or from 475° C. to 525° C., or from 490° C. to 510° C. invarious embodiments.

Referring to FIG. 1, the method further may include preheating thehydrocarbon feed 4 upstream of the catalyst bed reactor 10. Thispreheating of the hydrocarbon feed 4 may be achieved in a preheater 12.As shown, the hydrocarbon fed 4 may be heated in the presence ofnitrogen 6 and air 8. Additionally, the hydrocarbon fed 4 may be heatedin the presence of steam, hydrogen, air, oxygen, or their combinations.In one embodiment, the preheater 12 may raise the temperature of thehydrocarbon feed being supplied to the catalyst bed reactor 10 to atleast 200° C. Feed preheaters help alleviate cooling of the top of thecatalyst bed reactor 10 with a cold feed which in turn would affectcatalyst performance.

In one or more embodiments, the hydrocarbon cracking system 100 may alsoinclude at least one hydrocarbon preheater 18 disposed upstream of thepreheater 12. The hydrocarbon preheater or preheaters 18, as shown inFIG. 1, raises the temperature of the hydrocarbon feed being supplied tothe at least one preheater 12. In further embodiments, the hydrocarbonpreheater 18 raises the temperature of the hydrocarbon feed beingsupplied to the at least one preheater 12 to at least 100° C. Thehydrocarbon preheaters 18 may include a heat exchanger or a similarheater device familiar to one of ordinary skill in the art.

The hydrocarbon cracking system 100 may also include other heatingcomponents as shown. For example, the hydrocarbon cracking system 100may include a reactor oven 20, or a hot box 22 surrounding the catalystbed reactor 10, the preheater 12, and the hydrocarbon preheater 18. Thereactor oven 20 may help maintain the temperature of the catalyst bedreactor 10 and the preheater 12 in a laboratory scale or pilot unit.Similarly, the hot box 22 serves to retain heat around the catalyst bedreactor 10, the preheater 12, and the hydrocarbon preheater 18 so as toreduce thermal losses.

Referring again to FIG. 1, the cracking product 40 may comprise avariety of light C₁-C₄ hydrocarbons and heavy C₅₊ hydrocarbons. In oneor more embodiments, the cracking product 40 specifically comprisespropylene, butenes such as 2-trans-butene, n-butene, iso-butene and2-cis-butene, C₅ olefins, aromatics, methane, ethane, propane, butanes,and pentane. The constituents of the cracking product 40 are dependentupon the components of the hydrocarbon feed 4 and the properties of boththe cracking catalyst and the metal oxide.

To separate light hydrocarbons from heavy hydrocarbons in the crackingproduct 40, the hydrocarbon cracking system 100 may also include atleast one liquid/gas separator 24. The liquid/gas separator 24, whichmay include a flash drum or the like, separates the cracking product 40into multiple product streams based on the boiling point of individualcomponents of the cracking product 40. Specifically in the liquid/gasseparator 24, the light hydrocarbon stream 42 may evaporate out of thetop of the liquid/gas separator 24 as gas phase light hydrocarbons,while the liquid phase heavy hydrocarbon stream 44 is discharged fromthe bottom of the liquid/gas separator 24.

Further reactions are contemplated to separate the desired propylene andethylene from the light hydrocarbon stream 42. For example, the lighthydrocarbon stream 42 may be cooled and collected as a liquidhydrocarbon product. At which point, propylene and ethylene may beseparated via a distillation or extraction methodology.

In further embodiments, steam is additionally supplied to thehydrocarbon cracking system 100 to control the space velocity of thereaction. In embodiments, deionized water is passed through anevaporator or superheater to feed stream directly into the catalyst bedreactor 10. Such an arrangement may provide superheated stream up to400° C. to the catalyst bed reactor 10. The weight hourly space velocity(WHSV) is defined as the weight of entering feed per hour (hr) dividedby the weight of the catalyst. In various embodiments, the WHSV of thereaction is 1 to 100 hours⁻¹ (hr⁻¹), 3 to 9 hr⁻¹, 3 to 4 hr⁻¹, and 8 to9 hr⁻¹ and varies depending on the type of reaction to be catalyzed.

The limiting factor for reaction time with the heat generating catalystis the metal oxide loading. Specifically, the heat generated fromreduction of the metal oxides subsides prior to deactivation of thecracking catalyst. As such, in at least one embodiment, hydrogen orother flammable species may be selectively burned in a separate reactorto generate additional heat to fuel the endothermic hydrocarbon crackingreaction beyond the period where the reducing metal oxide suppliesadditional heat to the active sites of the cracking catalyst.

Examples

The following examples are illustrative of the present embodiments andare not intended to limit the scope of the described embodiments of thedisclosure.

Example 1—CuO/H-ZSM-5 Catalyst

H-ZSM-5 catalyst with a Si/Al weight ratio of 38 loaded withapproximately 20 wt % copper (II) oxide was prepared. Copper nitratetrihydrate (Cu(NO₃)₂.3H₂O) available from Sigma-Aldrich was provided asthe metal oxide precursor. 11.4 grams (g) of the copper nitratetrihydrate was dissolved completely in 3.7 g of deionized water.Subsequently, the Copper nitrate trihydrate dissolved in the deionizedwater was added drop-wise to 15 g of lightly crushed ZSM-5 whilestirring. The resulting solid was dried in an oven at 110° C. for 4hours and then calcined in air at 650° C. for 4 hours. FIG. 2 shows anoutput image from back-scattered electron scanning electron microscopy(BSE-SEM) of the CuO/H-ZSM-5 catalyst. Additionally, inductively coupledplasma (ICP) analysis confirmed a final 19.9% copper oxide loading onthe zeolite catalyst.

With reference to FIG. 3, a temperature programmed reduction (TPR) testfor 20% CuO supported on alumina is provided. A sample of CuO supportedon alumina was prepared for this test to singly determine the reductionbehavior of copper. The TPR test confirms that CuO can be reduced andgenerate heat at reaction temperatures over 350° C.

Example 2—FeO/H-ZSM-5 Catalyst

H-ZSM-5 catalyst with a Si/Al weight ratio of 38 loaded with mixed iron(II & III) oxides was prepared. 15 g of the mixed iron (II & III) oxideswere added to 15 g of the H-ZSM-5 and 20 g of α-Alumina as a binder.Subsequently, 30 g of water was added to generate a consistency whichallowed easy extrusion through a syringe. The mixture was then extrudedand dried overnight at 100° C. After drying, the mixture was calcinedunder air at 750° C. for 4 hours (hrs).

Example 3—CoO/H-ZSM-5 Catalyst

H-ZSM-5 catalyst with a Si/Al weight ratio of 38 loaded withapproximately 20 wt % cobalt oxide was prepared. Cobalt(II) nitratehexahydrate (Co(NO₃)₂.6H₂O) was provided as the metal oxide precursor.14.6 grams (g) of the cobalt(II) nitrate hexahydrate was dissolvedcompletely in 4.57 g of deionized water. Subsequently, the cobalt(II)nitrate hexahydrate dissolved in the deionized water was added drop-wiseto 15 g of lightly crushed ZSM-5 while stirring. The resulting solid wasdried in an oven at 110° C. for 4 hours and then calcined in air at 650°C. for 4 hours.

Example 4—CrO/H-ZSM-5 Catalyst

H-ZSM-5 catalyst with a Si/Al weight ratio of 38 loaded withapproximately 20 wt % chromium oxide was prepared. Chromium (III)nitrate nonahydrate (Cr(NO₃)₃.9H₂O) was provided as the metal oxideprecursor. 22.1 grams (g) of the chromium (III) nitrate nonahydrate wasdissolved completely in 13.9 g of deionized water. Subsequently, thechromium (III) nitrate nonahydrate dissolved in the deionized water wasadded drop-wise to 15 g of lightly crushed ZSM-5 while stirring. Theresulting solid was dried in an oven at 110° C. for 4 hours and thencalcined in air at 650° C. for 4 hours.

The improved conversion of the hydrocarbon feed 4 and light olefin (forexample, ethylene and propylene) yields are validated with experimentaltesting. Experimental data was obtained to demonstrate the effect ofmodifying the zeolite catalyst with metal oxides. Catalytic reactionswere carried out in a fixed-bed flow reactor system and fluidized risersimulator. For the fixed bed experiments, hexane was provided to anexperimental set-up of the hydrocarbon cracking system 100 under varyingconditions.

Catalyst prepared in accordance with example 1 was loaded into thereactor. For each example, the zeolite catalyst of H-ZSM-5 with a Si/Alweight ratio of 38 was acquired from Nankai University Catalyst Company.The zeolite catalyst contains 30% by weight gamma Alumina as a binder.The unmodified catalyst for comparative unmodified catalyst testing wasH-ZSM-5 with a Si/Al ratio of 38 which was crushed and sieved to aparticle size in the range of 5 to 850 nanometers (nm) or 250 to 850 nm,or 425 to 850 nm. Additionally N-hexane for the hydrogen feed wasacquired from Sigma-Aldrich and was high performance liquidchromatography (HPLC) grade.

The fixed-bed flow reactor system has two tubular reactors connected inseries. The catalyst for testing, for example, the CuO/H-ZSM-5 catalystof example 1, was mounted in the second reactor while the first reactorwas utilized to preheat the hexane feed to reaction temperature. Feedpreheaters improve energy efficiency of the process. Additionally, if acold feed is introduced directly into a catalyst bed, the top section ofthe catalyst bed will cool and reduce performance of the reactor as wellas affect conversion and selectivity. The fresh catalyst was firstactivated at 550° C. under airflow at 0.154 liters/minute (1/min) for 1hour. At the desired reaction temperature the n-hexane was introducedinto the reactor to start the reaction. The reaction was performed at550° C. and at a WHSV of 3.5 hr⁻¹, using nitrogen as a diluent.

With reference to FIG. 4, a comparison of the catalyst bed temperatureprofile as the reaction time progresses is provided. The catalyst bedtemperature was measured using a 3 point thermocouple mounted inside thecatalyst bed. The reaction was performed at 550° C. and at a WHSV of 3.5hr⁻¹, using nitrogen as a diluent. The catalyst bed temperature for anunmodified H-ZSM-5 catalyst held steady at the reaction temperature of550° C. Conversely, the modified CuO/H-ZSM-5 catalyst prepared inaccordance with example 1 resulted in a distinct exothermic reaction.The catalyst bed temperature quickly rose from the starting reactiontemperature of 550° C. to over 597° C. demonstrating the exothermicityof the reaction before decreasing as the reaction progressed. The steadydecrease of the catalyst bed temperature after the initial spike isbelieved to be the result of extinction of oxidized metal species as theoxidized metal species are reduced resulting in a decrease in thegeneration of additional heat. The modified catalyst resulted in anexothermic reaction which yielded a nearly 50° C. increase in thecatalyst bed temperature at the chosen reaction conditions. To eliminatethe effect of the controller, the temperature of the oven was set acertain temperature that kept the catalyst bed at 550° C. under the flowof nitrogen. Thus, when the feed was introduced, any temperatureincrease or decrease could be attributed to the reaction and not theeffects of the controller.

The demands on the external heating functionality of the fixed-bedreactor system to maintain the catalyst bed temperature during theexothermic cracking reaction increases as the flow rate of hydrocarbonfeed increases through the reactor. With reference to FIG. 5, acomparison of the catalyst bed temperature profile as the reaction timeprogresses is provided. The reaction was performed at 550° C. and at aWHSV of 8.4 hr⁻¹, using nitrogen as a diluent. The reaction parameterswere that same as with FIG. 4, but the WHSV was changed to 8.4 hr⁻¹.With the increased hydrocarbon flow rate through the reactor, themodified CuO/H-ZSM-5 catalyst prepared in accordance with example 1resulted in the catalyst bed temperature bed holding substantiallysteady at 550° C. Conversely, the unmodified H-ZSM-5 catalyst resultedin a dip of the catalyst bed temperature down to 525° C. from theinitial catalyst bed temperature of 550° C. The modification of spacevelocity and hydrocarbon to catalyst ratio resulted in a thermo-neutralreaction for the modified CuO/H-ZSM-5 catalyst prepared in accordancewith example 1.

The initial catalyst bed temperature also effects heat generation fromthe modified H-ZSM-5 catalyst. With reference to FIG. 6, a comparison ofthe catalyst bed temperature profile as the reaction time progresses isprovided with different initial catalyst bed temperatures. The reactionwas performed at 588° C. and at a WHSV of 8.4 hr⁻¹, using nitrogen as adiluent. The reaction parameters were that same as with FIG. 5, but theinitial catalyst bed temperature was increased from 550° C. to 588° C.With the increased initial catalyst bed temperature, the modifiedCuO/H-ZSM-5 catalyst prepared in accordance with example 1 generatedmore heat initially resulting in a spike of the catalyst bed temperaturefrom 588° C. to over 625° C. Conversely, the modified CuO/H-ZSM-5catalyst reacted with an initial catalyst bed temperature of 550° C.resulted in a steady catalyst bed temperature of 550° C. with nosubstantial spike. Thus, the heat generated at higher catalyst bedtemperatures is more than enough to fuel the desired hydrocarboncracking process under these reaction conditions. A thermal neutralprocess can be reached at 550° C. under these reaction conditions and athermally positive process can be reached at 588° C. under theseconditions.

Subsequent experimental data was obtained with catalyst prepared inaccordance with examples 1, 3 and 4 as well as unmodified H-ZSM-5catalyst in a CREC (Chemical Reactor Engineering Centre at University ofWestern Ontario) riser simulator batch unit. A CREC riser simulatorbatch unit is a batch reactor that closely reproduces reactionconditions of industrial continuous “riser” and “downer” units allowingcost effective research and development of new catalytic processes. TheCREC riser simulator batch unit is commercialized under exclusivelicense by Reactor Engineering and Catalytic Technologies Inc. (London,Ontario, CANADA). The cracking reactions were performed with a reactorcatalyst loading fixed at 0.4 g and a reactant residence time of 5seconds (s). Additionally, all tests were performed at 550° C. and witha catalyst to oil ratio of 0.7 and residence time of 5 s.

The testing of examples 1, 3 and 4 as well as unmodified H-ZSM-5catalyst in a CREC riser simulator batch unit under the same processparameters allows for direct comparison of the modifications of examples1, 3 and 4 with unmodified H-ZSM-5 catalyst. The conversion of the feedhydrocarbon as well as the C₂ and C₃ yield percentages for each of thesamples is provided subsequently in Table 1. As previously indicated,Hexane was the feed hydrocarbon for the experimental set-up. Theconversion and yield percentages are based on weight percentages.Specifically, Hexane conversion is provided as formula [1] and yield ofthe individual products is provided as formula [2].

$\begin{matrix}{{{Hexane}\mspace{14mu} {Conversion}} = {\frac{\begin{pmatrix}{{{Mass}\mspace{14mu} {of}\mspace{14mu} {hexane}\mspace{14mu} {fed}} -} \\{{Mass}\mspace{14mu} {of}\mspace{14mu} {hexane}\mspace{14mu} {in}\mspace{14mu} {products}}\end{pmatrix}}{{Mass}\mspace{14mu} {of}\mspace{14mu} {hexane}\mspace{14mu} {fed}} \times 100}} & {{Formula}\mspace{14mu}\lbrack 1\rbrack} \\{{{Yield}\mspace{14mu} {of}\mspace{14mu} {product}\mspace{14mu} i} = {\frac{\left( {{Mass}\mspace{14mu} {of}\mspace{14mu} i} \right)}{{Mass}\mspace{14mu} {of}\mspace{14mu} {hexane}\mspace{14mu} {fed}} \times 100}} & {{Formula}\mspace{14mu}\lbrack 2\rbrack}\end{matrix}$

TABLE 1 Catalyst Conversion C₂ Yield % C₃ Yield % Unmodified H-ZSM-5 445.4 7.5 Example 1 40 15 16.1 CuO/H-ZSM-5 Example 3 40 9.4 14.3CoO/H-ZSM-5 Example 4 41 6.3 10 CrO/H-ZSM-5

The results of the testing of examples 1, 3 and 4 as well as unmodifiedH-ZSM-5 catalyst in a CREC riser simulator batch unit provided in Table1 demonstrate an increase in lighter olefin yield such as ethylene andpropylene with modification of the H-ZSM-5 catalyst. Additionally, evenwith 20% metal oxide loading, as with examples 1, 3, and 4, thecompromise in overall conversion of the hydrocarbon feed is notsignificant. The copper modified catalyst of example 1 revealed thehighest olefin yield enhancement followed by cobalt and chromium.

It should now be understood that the various aspects of the methods ofmaking a heat generating catalyst for hydrocarbon cracking are describedand such aspects may be utilized in conjunction with various otheraspects.

In a first aspect, the disclosure provides a method of making a heatgenerating catalyst for hydrocarbon cracking. The method comprisesproviding at least one mordenite framework-inverted (MFI) zeolitecatalyst having a Si/Al molar ratio of 15 or greater, providing at leastone metal oxide precursor; dispersing the at least one metal oxideprecursor within a microstructure of the MFI zeolite catalyst, andcalcining the heat generating catalyst with the at least one metal oxideprecursor dispersed within the microstructure of the MFI zeolitecatalyst to form at least one metal oxide in situ. Further, the ratio ofthe MFI zeolite catalyst to the metal oxide is in the range of 50:50 to95:5 on a weight basis.

In a second aspect, the disclosure provides the method of the firstaspect, in which the at least one metal oxide precursor is dispersedwithin the microstructure of the MFI zeolite catalyst via at least oneof wet impregnation, precipitation, electrolysis deposition,deposition-precipitation, chemical vapor deposition, and flame spraypyrolysis.

In a third aspect, the disclosure provides the method of the first orsecond aspects, in which the at least one metal oxide is at least one ofan oxide of iron, copper, zinc, chromium, molybdenum, vanadium, cerium,manganese, bismuth, silver, cobalt, vanadium, zirconium, tungsten,magnesium, and their combinations.

In a fourth aspect, the disclosure provides the method of the thirdaspect, in which the at least one metal oxide comprises copper oxide.

In a fifth aspect, the disclosure provides the method of any of thefirst through fourth aspects, in which the metal oxide precursor is ahydrate of a metal salt of nitric acid.

In a sixth aspect, the disclosure provides the method of any of thefirst through fifth aspects, in which the metal oxide precursor iscopper nitrate trihydrate (Cu(NO₃)₂.3H₂O), cobalt (II) nitratehexahydrate (Co(NO₃)₂.6H₂O), or chromium (III) nitrate nonahydrate(Cr(NO₃)₃.9H₂O).

In a seventh aspect, the disclosure provides the method of any of thefirst through sixth aspects, in which dispersing the metal oxideprecursor within the microstructure of the MFI zeolite catalystcomprises dissolving the metal oxide precursor in water and addingdrop-wise to the MFI zeolite.

In an eighth aspect, the disclosure provides the method of any of thefirst through seventh aspects, in which the at least one metal oxide ischemically bonded to the microstructure of the MFI zeolite catalyst.

In a ninth aspect, the disclosure provides the method of the seventhaspect, in which the MFI zeolite catalyst is crushed ZSM-5 catalysthaving an average particle size of 5 to 850 nanometers.

In a tenth aspect, the disclosure provides the method of the ninthaspect, in which the ZSM-5 catalyst is an H-ZSM-5 catalyst.

In an eleventh aspect, the disclosure provides the method of any of thefirst through tenth aspects, in which calcining the heat generatingcatalyst is done in air at 400° C. to 800° C. for sufficient time toconvert the metal oxide precursor to a metal oxide in situ.

In a twelfth aspect, the disclosure provides the method of any of thefirst through eleventh aspects, in which the heat generating catalystfurther comprises a promoter.

In a thirteenth aspect, the disclosure provides the method of thetwelfth aspect, in which the promoter is at least one of an alkalimetal, an alkaline earth metal, a rare earth metal, a transition metal,phosphorous, and their combinations.

In a fourteenth aspect, the disclosure provides a method of using a heatgenerating catalyst in a hydrocarbon cracking process. The methodcomprises providing a catalyst bed reactor, introducing a hydrocarbonfeed to the catalyst bed reactor, and cracking the hydrocarbon feed toproduce a cracking product. The catalyst bed reactor includes a catalystbed of the heat generating catalyst disposed in the catalyst bedreactor. The heat generating catalyst comprises at least one mordeniteframework-inverted (MFI) zeolite catalyst having a Si/Al molar ratio of15 or greater, and at least one metal oxide dispersed within amicrostructure of the MFI zeolite catalyst.

In a fifteenth aspect, the disclosure provides the method of thefourteenth aspect, in which the catalyst bed reactor comprises afluidized bed reactor or a fixed-bed reactor.

In a sixteenth aspect, the disclosure provides the method of any of thefourteenth through fifteenth aspects, in which the catalyst bed reactoris a fixed-bed reactor and the catalyst bed of the heat generatingcatalyst comprises a layer of the heat generating catalyst disposedbefore a layer of MFI zeolite catalyst, a layer of heat generatingcatalyst disposed after a layer of MFI zeolite catalyst, or at least onelayer of heat generating catalyst disposed between at least two layersof MFI zeolite catalyst.

In a seventeenth aspect, the disclosure provides the method of any ofthe fourteenth through sixteenth aspects, in which the at least onemetal oxide is chemically bonded to the microstructure of the MFIzeolite catalyst.

In an eighteenth aspect, the disclosure provides the method of any ofthe fourteenth through seventeenth aspects, in which the heat generatingcatalyst further comprises a promoter.

In a nineteenth aspect, the disclosure provides the method of any of thefourteenth through eighteenth aspects, in which the promoter is at leastone of an alkali metal, an alkaline earth metal, a rare earth metal, atransition metal, phosphorous, and their combinations.

In a twentieth aspect, the disclosure provides the method of any of thefourteenth through nineteenth aspects, in which the MFI zeolite catalystis a ZSM-5 catalyst.

In a twenty-first aspect, the disclosure provides the method of thetwentieth aspect, in which the ZSM-5 catalyst is a H-ZSM-5 catalyst.

It should be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedhere without departing from the spirit and scope of the claimed subjectmatter. Thus it is intended that the specification cover themodifications and variations of the various embodiments described hereprovided such modification and variations come within the scope of theappended claims and their equivalents.

Throughout this disclosure ranges are provided. It is envisioned thateach discrete value encompassed by the ranges are also included.Additionally, the ranges which may be formed by each discrete valueencompassed by the explicitly disclosed ranges are equally envisioned.

What is claimed is:
 1. A method of making a heat generating catalyst forhydrocarbon cracking, the method comprising: providing at least onemordenite framework-inverted (MFI) zeolite catalyst having a Si/Al molarratio of 15 or greater; providing at least one metal oxide precursor;dispersing the at least one metal oxide precursor within amicrostructure of the MFI zeolite catalyst; calcining the heatgenerating catalyst with the at least one metal oxide precursordispersed within the microstructure of the MFI zeolite catalyst to format least one metal oxide in situ, where the ratio of the MFI zeolitecatalyst to the metal oxide is in the range of 50:50 to 95:5 on a weightbasis.
 2. The method of claim 1 where the at least one metal oxideprecursor is dispersed within the microstructure of the MFI zeolitecatalyst via at least one of wet impregnation, precipitation,electrolysis deposition, deposition-precipitation, chemical vapordeposition, and flame spray pyrolysis.
 3. The method of claim 1 wherethe at least one metal oxide is at least one of an oxide of iron,copper, zinc, chromium, molybdenum, vanadium, cerium, manganese,bismuth, silver, cobalt, vanadium, zirconium, tungsten, magnesium, andtheir combinations.
 4. The method of claim 3 where the at least onemetal oxide comprises copper oxide.
 5. The method of claim 1 where themetal oxide precursor is a hydrate of a metal salt of nitric acid. 6.The method of claim 5 where the metal oxide precursor is copper nitratetrihydrate (Cu(NO₃)₂.3H₂O), cobalt (II) nitrate hexahydrate(Co(NO₃)₂.6H₂O), or chromium (III) nitrate nonahydrate (Cr(NO₃)₃.9H₂O).7. The method of claim 5 where dispersing the metal oxide precursorwithin the microstructure of the MFI zeolite catalyst comprisesdissolving the metal oxide precursor in water and adding drop-wise tothe MFI zeolite.
 8. The method of claim 1 where the at least one metaloxide is chemically bonded to the microstructure of the MFI zeolitecatalyst.
 9. The method of claim 7 where the MFI zeolite catalyst iscrushed ZSM-5 catalyst having an average particle size of 5 to 850nanometers.
 10. The method of claim 9 where the ZSM-5 catalyst is anH-ZSM-5 catalyst.
 11. The method of claim 1 where calcining the heatgenerating catalyst is done in air at 400° C. to 800° C. for sufficienttime to convert the metal oxide precursor to a metal oxide in situ. 12.The method of claim 1 where the heat generating catalyst furthercomprises a promoter.
 13. The method of claim 12 where the promoter isat least one of an alkali metal, an alkaline earth metal, a rare earthmetal, a transition metal, phosphorous, and their combinations.
 14. Amethod of using a heat generating catalyst in a hydrocarbon crackingprocess, the method comprising: providing a catalyst bed reactor, wherethe catalyst bed reactor includes a catalyst bed of the heat generatingcatalyst disposed in the catalyst bed reactor, the heat generatingcatalyst comprising: at least one mordenite framework-inverted (MFI)zeolite catalyst having a Si/Al molar ratio of 15 or greater, and atleast one metal oxide dispersed within a microstructure of the MFIzeolite catalyst; introducing a hydrocarbon feed to the catalyst bedreactor; and cracking the hydrocarbon feed to produce a crackingproduct.
 15. The method of claim 14 where the catalyst bed reactorcomprises a fluidized bed reactor or a fixed-bed reactor.
 16. The methodof claim 15 where the catalyst bed reactor is a fixed-bed reactor andthe catalyst bed of the heat generating catalyst comprises a layer ofthe heat generating catalyst disposed before a layer of MFI zeolitecatalyst, a layer of heat generating catalyst disposed after a layer ofMFI zeolite catalyst, or at least one layer of heat generating catalystdisposed between at least two layers of MFI zeolite catalyst.
 17. Themethod of claim 14 where the at least one metal oxide is chemicallybonded to the microstructure of the MFI zeolite catalyst.
 18. The methodof claim 14 where the heat generating catalyst further comprises apromoter.
 19. The method of claim 18 where the promoter is at least oneof an alkali metal, an alkaline earth metal, a rare earth metal, atransition metal, phosphorous, and their combinations.
 20. The method ofclaim 14 where the MFI zeolite catalyst is a ZSM-5 catalyst.